The detection of superparamagnetic nanoparticles using NMR logging has the potential to provide enhanced contrast in oil reservoir rock formations. The stability of the nanoparticles is critical because the NMR relaxivity (R(2) ≡ 1/T(2)) is dependent on the particle size. Here we use a molecular theory to predict and validate experimentally the stability of citric acid-coated/PEGylated iron oxide nanoparticles under different pH conditions (pH 5, 7, 9, 11). The predicted value for the critical surface coverage required to produce a steric barrier of 5k(B)T for PEGylated nanoparticles (MW 2000) was 0.078 nm(-2), which is less than the experimental value of 0.143 nm(-2), implying that the nanoparticles should be stable at all pH values. Dynamic light scattering (DLS) measurements showed that the effective diameter did not increase at pH 7 or 9 after 30 days but increased at pH 11. The shifts in NMR relaxivity (from R(2) data) at 2 MHz agreed well with the changes in hydrodynamic diameter obtained from DLS data, indicating that the aggregation behavior of the nanoparticles can be easily and quantitatively detected by NMR. The unexpected aggregation at pH 11 is due to the desorption of the surface coating (citric acid or PEG) from the nanoparticle surface not accounted for in the theory. This study shows that the stability of the nanoparticles can be predicted by the theory and detected by NMR quantitatively, which suggests the nanoparticles to be a possible oil-field nanosensor.

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Recently, meta-analysis studies reported that hyperuricaemia is associated with higher incidence of type 2 diabetes mellitus (T2DM), however, there are limited data on the Asian population. The aim of this observational study is to estimate the long-term impact of hyperuricaemia on the new-onset T2DM and cardiovascular events. This study is based on a single-centre, all-comers, and large retrospective cohort. Subjects that visited from January 2004 to February 2014 were enrolled using the electronic database of Korea University Guro Hospital. A total of 10 505 patients without a history of T2DM were analyzed for uric acid, fasting glucose and haemoglobin (Hb) A1c level. Inclusion criteria included both Hb A1c <5.7% and fasting glucose level <100 mg/dL without T2DM. Hyperuricaemia was defined as a uric acid level ≥7.0 mg/dL in men, and ≥6.5 mg/dL in women. To adjust baseline confounders, a propensity score matching (PSM) analysis was performed. The impact of hyperuricaemia on the new-onset T2DM and cardiovascular events were compared with the non-hyperuricaemia during the 5-year clinical follow-up. After PSM, baseline characteristics of both groups were balanced. In a 5-year follow-up, the hyperuricaemia itself was a strong independent predictor of the incidence of new-onset T2DM (HR, 1.78; 95% CI, 1.12 to 2.8). Hyperuricaemia was a strong independent predictor of new-onset T2DM, which suggests a substantial implication for a correlation between uric acid concentration and insulin resistance (or insulin sensitivity). Also, hyperuricaemia is substantially implicated in cardiovascular risks and the further long-term cardiovascular events in the crude population, but it is not an independent predictor of long-term cardiovascular mortality in the matched population.

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BackgroundThe impact of percutaneous coronary intervention (PCI) on chronic total occlusion in patients with well‐developed collaterals is not clear.Methods and ResultsA total of 640 chronic total occlusion patients with collateral flow grade ≥2 were divided into 2 groups; chronic total occlusion patients either treated with PCI (the PCI group; n=305) or optimal medical therapy (the optimal medical therapy group; n=335). To adjust for potential confounders, a propensity score matching analysis was performed. Major clinical outcomes were compared between the 2 groups up to 5 years. In the entire population, the PCI group had a lower hazard of myocardial infarction (hazard ratio [HR], 0.177; P=0.039; 95% confidence interval [CI], 0.03–0.91) and the composite of total death or myocardial infarction (HR, 0.298; P=0.017; 95% CI, 0.11–0.80); however, it showed higher hazard of target lesion revascularization (HR, 3.942; P=0.003; 95% CI, 1.58–9.81) and target vessel revascularization (HR, 4.218; P=0.001; 95% CI, 1.85–9.60). After propensity score matching, a total of 158 matched pairs were generated. Although the PCI group showed a higher hazard of target lesion revascularization (HR, 2.868; P=0.027; 95% CI, 1.13–7.31) and target vessel revascularization (HR=2.62; P=0.022; 95% CI, 1.15–5.97), it still exhibited a lower incidence of the composite of total death or myocardial infarction (HR, 0.263; P=0.017; 95% CI, 0.087–0.790). The mean ejection fraction was improved from 47.8% to 51.6% (P<0.001) after PCI.ConclusionsIn our study, successful revascularization by PCI for chronic total occlusion lesions with well‐developed collaterals was associated with lower incidence of death and myocardial infarction, improved left ventricular function, but increased repeat revascularization rate.